THE HISTORICAL DEVELOPMENT OF AVIATION MEDICINE IN OUR COUNTRY IS REVIEWED. THE STRUCTURE OF THE EARTH'S ATMOSPHERE, A SURVEY OF HUMAN ANATOMY AND PHYSIOLOGY, AND THE EFFECT OF VARIOUS FLIGHT FACTORS ON MAN ARE ALSO DISCUSSED. THE PHYSIOLOGICAL AND HYGIENIC REQUIREMENTS FOR CABINS OF MODERN AIRCRAFT AND THE OXYGEN-RESPIRATION APPARATUS ARE SPECIFIED, ALONG WITH PARTICULAR ASPECTS OF FLIGHTS UNDER DIFFICULT METEOROLOGICAL CONDITIONS AND AT NIGHT AFFECTING THE PILOT'S BODY. THE PROBLEMS INVOLVED IN FEEDING A FLIGHT CREW ARE DISCUSSED.